Process for preparing monomeric stable methylolphenol compositions



Patented Sept. 2, 1952 PROCESS FOR PREPARING MoNoME Ic STABLE METHYLOLPHENOL coMPo- S-ITIONS Hamline M. Kvalnes, Wilmington, DeL, assignor I to E. I. du Pont de Nem'oursand Company,

Wilmington, Del., a corporation ofiDelaware' No rawing. Application May 22, Q1951;

Serial No. 227,761 i 15 Claims. (01. zoo-345.1).

This invention relates to certain novel and useful monomeric polymethylolphenol compositions, and to processes for preparing the same. It also relates to the preparation of novel viscous liquids from the said polymethylolphenols, which liquids have useful properties in the manufacture of phenol-formaldehyde resins.

It was known heretofore that phenol reacts relatively slowly with formaldehyde; i. e., that higher temperatures and catalyst concentrations have been required to obtain the same rate ,of reaction of formaldehyde with phenol as with other well-known resin intermediates such as urea, melamine or resorcinol. According to the previously known commercial practice, from 1 to 31molsof formalin were mixed with one mol of phenol, to produce a clearliquidw containing the unreacted ingredients in aqueous solution. Under moderately strongly alkaline 1 conditions, or very strongly acid conditions, methylolphenols were formed in such solutions, and these were convertible, by the action ofheat, to polymeric products. However, the methylolphenol solutions had very poor. storage properties, and after a few months'at roomtemperature such solutions were no.v longer homogeneoua' but" contained two layers,'viz.: (1) a lower resinous layerand (2): anupper aqueouslayer. IWhen theinitial form-. aldehyde: phenol mol ratio (Fl/P) was greater than 1 the lower layer eventually set to a gel. To avoid this separation of phases and formation of gel it has been found possible heretofore to employ compositions in which the pH was carefully controlled; mildly acidic conditionshad a very highly beneficial effect on thestorage properties of thesemethylolphenol solutions. However, when attempts were madetoproduce the Y same stabilizing effect on highly concentrated methylolphenols, prepared for example from 60% formaldehyde (+40% water), and phenoLproducts which became solid or opaque in from 1 to 24 hours were obtained. This disadvantage placed a limitation on the use of highly concentrated formaldehyde in themanufacture of phenolic resins. From an economic standpoint, it was'desirable to employ 60% formaldehyde for numerous applications in making phenolic resins, provided the technical difficulties just described could be overcome. Furthfilmore, it was also desirable, from an economic standpoint, for. certain 'other applications, to employ Very recently an important advance has been made in the commercial method for preparing resins other than phenolic resins, particularly urea resins,- using very concentrated 3 formaldehyde, e. g. it has been discovered that, in the manufacture of higher methylolureas; if one keeps monomeric formaldehyde at a high enough temperature to prevent polymerization of the formaldehyde prior to admixture with urea under methylolurea-forming condition, stable liq-' uid polymethylolureas can be obtained, which liquids remain clear for very extendedperiods of timeiKvalnes, Reissue Patent 23,174). It was not known, however, that any corresponding effect could also be achieved in the manufacture of highly concentrated polymethylol-phenol liqaldehyde takes place too slowly to permit preventing'the formation ofprecipita'tes by'using polymer-free formaldehyde initially, as could be done in the urea-formaldehyde art. Probably this, was because theprecipitates which formed were the result o f e cessive formaldehyde polymerization, which takes place preferentially in thephenol system, but not preferentially in the urea system.

An object of the present invention is to provide polymethylol phenol compositions which remain clear, at high concentrations, for relatively long periods or time. A further object is to provide a process for preparing methylolphenols from relatively concentrated aqueous formaldehyde, having a formaldehyde content inexcess of 58% by weight. Another object is to provide novel improvements in the art of condensing phenol with formaldehyde. Other objects will appear hereinafter.

It has been discovered, in accordance with this invention, that stable, clear, precipitate-free.

tur e at .a temperature within the range of 60 to l00 C. (preferably'80 '00-'90 C:) at a pH of hyde is brought into contact with the said phenol. 1

For prolonged storage at room temperature the final pH is preferably adjusted to 4.5-6.8, the optimum final pH being 5.5-6.5. Such products remain clear for prolonged periods of time. The products obtained as above'described can be bodied by heating at 70 to. 100 C. at .a pHv of 7.0 to 9.5, and the bodied products-can be admixed with a formaldehyde-reactive resin ingredient, e. g. urea (which maybe added alternatively prior to bodying) and the resulting mixture can be thermoset by heating at 120- to 1 175 C. If the added ingredient is phenol the thermosetting reaction takesplace under strongly acidic or alkaline conditions, whileifithe added ingredient urea, acidic thermosetting conditions-must be employed.

-'I'he amount of methylolation can be measured conveniently by analysis for free formaldehyde and determining the number of methylol groups by difference; of course, once this has been done it isalso possible to predetermine the degree of methylolati'on by-controlling the reaction time, with reference to the previously obtained data, such asthatcontained in the present specification.

' To illustrate the, effect of, free formaldehyde content on (the stability of the polymethylol phenol compositions, aseriesof experiments was made in,whic h. the mixtures of phenol and aqueousiformaldehyde were heated together (pH:8, Temp.:80 to 85 0.), using various F/Pratios (i. e. mol ratios of total formaldehydeztotal phenol). The resultsare set forth in the following table. The formaldehyde employed in these experiments was a clear monomeric aqueous liquid which was maintained at approximately 80 C. from the time when it was produceduntil it"was used.

, #Efi t of flee HCHOon stability or gooly'methylolphenols I Stability Methylol test (For- F P Free groups mation of I HCHO per precipitate phenol on storagefailure) Percent 6.0 '43. 3 0. l9 Failed. 7.0 40. 3 V 0.90 Do. 7.0 v 38.6 1.1) Do. 0. 37. 6 v 1.16 Do. 6. 34. 9 l. 3% 0.1-1. 6. 32. 6 1. 50 o. k. 5. 3 1. 6 1. 55 o. 1:. 6. 31. 0 1. 73 0. k. 5. 30. l. 42 0. k. 4. 30. 0 1. 0. k. 0. 20. l 2. 13 o. k. 6. 2:8. 3 2. o. k. 6-. 2S. 3 2. 25 0. k. 6. 26. 3 2. 5i 0. k. 4. 22. 5 1.65 0.1:.

When the F/P ratiois 10, a 'trimethylol phenol 4 containing about 35% free formaldehyde, prepared as above described, is stable.

Data recorded in Table II show that it is necessary to employ a F/P ratio below 1 to obtain a stable liquid if the reaction mixture, made from 60% HCHO, is cooled quickly from C. to room temperature, without allowing time for methylolation to take place. As disclosed in the Kvalnes reissue patent, parallel experiments with urea instead of phenol do not produce an analogous result, for in the case of urea it is necessary to heat the methylolation mixture only momentarily, there being no difficulty due to polymerization of formaldehyde during the cooling of the methylolation mixture. Table II thus shows that the phenol methylolation mixture does not behave in a manner analogous to the behavior of the urea methylolation mixture of the Kvalnes reissue patent.

TABLE II -Ned for low F/P ratios in making clear solutions from 60% formaldehyde prior to methylolation {Mixtures of 38% phenol (aqueous), adjusted to pH 8 with 20% sodium hydroxide, and 60% formaldehyde (aqueous were prepared by adding formaldehyde at 80 0. to phenol at room temperature. The formaldehyde was a clear liquid which had been maintained at approximately 80 C. i'rom'the time of its preparation untilthe time of its use. l he'clear solutions were cooled rapidly to room temperature and adjusted to pH 6.5 with 10% hydrochloric acid as shown in the table below; only the sample at an F/P ration of less than 1.0 was stable on storegal T,.'Ihe following examples further illustrate the conditions required for the production of clear polymethylol phenol compositions. The first ex-. ample illustrams the difiiculty of effecting stabilization of a polymethylolphenol solution containing polymeric formaldehyde. In that example, the methylolphenol was prepared from monomeric formaldehyde under the conditions specified, and after 20 minutes heating the unreacted. formaldehyde which remained in the mixture polymerized on storage. To effect methylolation from this polymeric formaldehyde it was necessary to heat the mixture for the prohibitively long time of 15 hours. Example 1 shouldbe compared with Example 2, because in. Example 2 itis shown that when the methylolationis'continued until the free formaldehyde falls below 35%, this difliculty is not encountered.

Example 1.Samp1es.of F/P 4.8 and F/P 6.0 were prepared as follows: 85.5% synthetic phenol ,(rernainder HzO) was adjusted to pI-I 8 with 20% sodium hydroxide and heated to 40 C. Then 00.5% formaldehyde (remainder HzO), which had never been permitted to cool below 80 0., was added and the pH was again adjusted to 8. Thecharge was then heated at 80 to C. for 20 minutes while maintaining the pI -I at 7 to 8. The resulting clear. liquids were cooled rapidly to room temperature. After one day at roomtemperature the products were opaque. Additional" heating was required to obtain liquids which remained clear on storage at room temperature. This is shown in the following table.

I "I licit: III.-.F 17ect'of methg lo'i andjree-formaZd-f c v i hyde content on clarity of, methyblphenol liquids Test No F11. momma... 4.8 6.0 T v I A 20 minutes/85 CJpH 7 to 8: (l) Stored 1 day at roomftemp p .-'opaqu e opaque Time required to dissolve paraformaldehyde thus produced: -'hours/60 C./ 16 hours/609,0.l f

pH7to8 pH7to8'jf"' (1) Stored 5 months at room temp clear clear w l aqueous formaldehyde (which had notbeen per: mitted to cool below 80 C.) was added to 263 grams of 88% -US P phenol which had been adjus tcdto pH 8 with 2 sodiumhydroxide. v IIhe mixture (F/P=6:1) was reacted as shown in the followingtable. 4

Example 2.'73'7 grams of 60.9% clear, liquid, 15 polymerization ofteither, formaldehyde, the

methylolphenola orI both. Once a sufficient amountof methylolation is effected, a balance. or equilibrium, appears to. prevail, whereby in some manner not necessarily understood polymerization of the remainingfree formaldehyde no longer takes place, orat least does not pro- ITABLE IV.-E17ect of reaction ta -a7; degree of I methylolatio'n ;Methylol f 'Ternp CC.) pH gg Groups'l S ample at Room Temp. H

Phenol of 20% sodiutn hydroxide added during the run. I V V Easdmple 3.Mixtures of88% USP phenol and duce a: solid phase. This is especially notice;

60% formaldehyde (which had not been-permitted to' cool below 80 C.) of various F/Bmol ratios were reacted at approximately 85 C. and pH 8 to 9 for 1-5 minutes. The properties of the products are given in the following table; -"1his series of experiments again shows that at free formaldehyde contentsbelow' 35%fprecipitates db -not form. It also shows that for 'F/Pfratios of-6'.-2 and below, under the conditions" ofthe example-"the free formaldehyde content is r educed to the level required for; avoiding form aldehyde polymerization, in a reaction time of 9-to15minutes.

of methylolphenols able if 'the'pI-I of the final product is-adju'sted to about5.0 to 6.0 prior to storage. y "Ihe'methylolation step should preferably'not be carried outata pH higher than 9.5, because 4 higher'allgalinities result in destruction of'forl naldehydejfThere is a range of pH onth'e'jacid side I within 'which' methylolation -can be eii fe cted without rapid polymerization, namely at about pl-141 Nevertheless, the present invention is not directed to the use of an acidic mixture in the methylolation step; The alkaline methylolation step is preferred over an acidic methylolation step, because on the acid side, at the pH which is TABLE l/ect of F/P mol ratio on. stability- Y Test No. 7 1 8'. 9 10 11 12 1. F/P mol ratio 6:8 6. 2 5 2 4. 7 4.1 3. 1 2; Total formaldehyde, percent 45.36 44.40 4 42.01: 40.38- 38.04 1.34200 1 3. Total phenol, percent 21.09 22.34 h 25. 39 2'1. 17 29. .42 34. 93 4]; z'ictiie resin solids, percent 66. 45 66. 74 67.40 67155 67:46 68. 98 r0 uc: 1t 5. Free formaldehyde, percent 35.6 33:5 .3l.-0 30.6 .1 22.0 18.0 6. 'Methylol groups/phenol 1.5 1:4 1.4 1.5 "-1.7 2.4 7. Viscosity, cp., 25 C 15 15 1 15" 15 25 V 25 8. Freezing point, C -27.5 25 9. Specific gravity, F l. 19 1.19 1. 19 1.19 1. 19 1. 18 10. R. I., 25,0 1. 454 1.456 I 1.467 1.462 11.477, 1.483 1L Water miscibility zero complete complete complete complete complete 12; Appearance (2 months at room -temp.) opaque. clear clear clear clear I clear not clear. An important aspect of the invention is therefore the discovery of the conditions required for, effecting ,methlolation in preference 05 not so low as to produce rapid polymerization,

the rate of methylolation .is too slow, asshown in the following test: Av mixture of 88%--USP phenol and monomeric 60%. liquid formaldehyde (both'aqueous) was heated at 85C. and a pH of 4.0 for 15 minutes, giving a mixture having a free formaldehyde content of 43.3% which wasver-y close to the free formaldehyde content of .the initial reaction mixture (cf/test i8 of Table V, showing much more rapid methylolaa tion'at a pH'of 8 to'9). 1 r

The unpolymerized methylolphenol compositions obtained by the method of this invention, hereinabove described, are referred to (for con-' venience) by the expression HMPs. The HMPs are useful in making resin intermediates and also in the manufacture of thermoset resins. The illustrations which follow show numerous useful properties of these resins and resin intermediates.

Preparation of viscous products from HMP wanoat adding other resin-forming ingredients A clear sample of higher methylolphenol containing five mols of formaldehyde per mol of phenol (F/P=) was prepared by heating at 90 C; 86% synthetic phenol (14% E) and 60% monomeric form-aldehyde (40% E20) at a pH of 8 until the free formaldehyde was reduced to- 19.4% methylol groups per unit of phenol). The resulting mixture was heated at 95 C. and pH 7.3 to 7.6 for 90 minutes. The viscosity increased from 25 cp. to 245 op. The viscous product thus obtained was clear and could be used in the manufacture of thermoset resins by the procedure hereinbelow described.

The preferred temperature for preparing viscous produces from HPM is about 70 to 100 C. (preferred pH, 7.0 to 9.5).

Preparation of viscous products from HMP and area A clear solution was prepared at room temperature by mixing 80 parts of higher methylolphenol solution (F/P=6, prepared by the method of Example 3).and 20 parts of urea. 'The resulting composition had a total formaldehyde content, free'i'and combined, of by weight. It'also containedj18%"by weight of combined phenol and 18% by weight of free urea. This solution was heated at 80 C. for 15 minutes at a pH of'7.2 to 7.8at the end of which time the viscosity was 40 cpl and the free formaldehyde was 0. The pH was then adjusted 'to 5.0 to 6.0 with 2.5% hydrochloric acid and the resultin nuxture washeated. at 80 for minutes after which 'the' resulting clear product. was cooled rapidly t room temperature. The clear liquid thus obtained had aviscosity of 165 cp. at 25 C.

The preferred temperature for preparing viscous products from HMP and urea is to 100 C. (preferred pH=7.0 to 9.5) until HGT-10:0.

Preparation of viscous products from HMP and added phenol Methylolphenols are readilyconverted to poly mers under alkaline conditions and a pH of 7.5 to 8.5 is preferred in preparing viscous compositions from mixtures of HMP and phenol. However, under acid conditions, even when the pH is as high as 4, the rate of polymer forming reaction is appreciable (as shown in Example 2).

A mixture consisting of 79 parts by weight of higher methyloyphenol solution (F/P=6.0, prepared by the method of Example 3) and 21 parts of 88% USP phenol was prepared at room temperature. This mixture contained 34.2% free and combined formaldehyde and 35.7% free and combined phenol. It was heated to 86 C. in 25 minutes, whereupon the free formaldehyde was 0.. The heating was continued at 90C. for an additional. 30. minutes at which time the pH was 6.15 (initial pH='i.3) and. the viscosity was 22 cp. (the. initial viscosity=15 cp.). ThepI-Iwas lowered to'4.0 with 5% hydrochloric. acid and the charge was heated for an additional 45 minutes,

the. product was cooled rapidly and adjusted to pH 6.7 with 20%sodii1mhyd'r0xide. The result- Preparation of a thermoset resin from HMP and area A higher methylolphenolsolution was prepared by adding 737 grams of 60.4% aqueous liquid formaldehyde (monomeric) at 61 C. to 263 grams of 87% USP phenol (pH-=). To the resulting mixture; at a temperatureof- 47- C. was added 13 ml. of 20% sodium hydroxide aqueous solution and the resulting mixture was heated 13090 C. in 19 minutes. The temperature of the mixture was maintained at to 90 C. for 15 minutes after which the mixture was cooled to room temperature.' To the clear solution thus obtained, having a pH of 8.4 was added 16 ml. of 10% hydrochloric acid which lowered the pH to 6.5. The free formaldehyde content of the resulting mixture. was 29.6; the viscosity: was 22 cp.; the specific gravity (60 F. /60 F), 1.201; the refractive index, 1460/25 C. This product was completely miscible with water and contained 43.3% free and combined formaldehyde and 22.2% combined phenol. An adhesive was prepared by adding to grams of this mixture, 22 grams of urea, 20 grams of walnut shell flour, and 0.35 gram of ammonium chloride. Douglas fir plywood panels /8" x 12' x 12") were bonded with this adhesive at a pressure of 1,50 lbs/sq. in. and a temperature of- C. for 10 minutes... Specimens of the resulting plywood were tested in a shear machine, after having been kept at 98% relative humidity at 75 0. for 2 4 hours. Averagewood failure was 33 and the average shear value was 230 lbs/sq. in. In this test the quantity of adhesive employed was 48 lbs./1000 sq. ft. of single glue line. In similar tests-with commercial urea formaldehyde adhesives using 59 lbs/1000 sq. ft, instead of 48 lbs/1000 sq. ft. the average wood 'failure was 7% and the average shear value was Preparation of a thermoset resin from viscous HMP solution and area An adhesive was prepared by mixing 100 grams of the viscous HMP-urea solution prepared from 80 grams HMP and 20 grams of urea by the method hereinabove described with 20 grams of walnut shell flour and 0.35 gram of ammonium chloride. Douglas fir plywood was prepared by the method described in the immediately preceding. experiment using 60 lbs. of this adhesive per 1000 sq. ft. of single glue line. When exposed to 98% relative humidity at 75 C. for 24 hours and tested in the shear machine, the specimens showed 87 %wood failure and had an average shear value of 200 lbs. per sa. in.

The preferred curing temperature, for HMP- urea is 120-to C.

Preparation of thermoset resin from a viscous mimtu're'obtained from HMP and added phenol, followed by bodyinq An adhesive was prepared by mixing 100 grams of HMP+phenol solution (34% total F, 36% total P, prepared by the method hereinabove described), 20 grams of walnut shell'flour and 0.35

gram of ammonium chloride. .Douglas'fir plywood was prepared using this adhesive in the manner described in the two experiments herephenol, is 120 to 175 C.

In addition to the methods for employing the compositions obtained in the practice of this invention hereinabove described, it is to be understood that numerous other useful applications of the said compositions may be made. For example, these uses include Wood impregnating compositions to increase the hardness, stability, and resistance to fungi, insects, marine borers, flame and outdoor exposure; assembly adhesives; adhesives to bond sawdust, metals, paper, etc.; production of plastics, ion exchange resins, foundry sand molds, foams, castings, brake linings, lacquers, varnishes and tanning agents; aqueous resin solutions to increase wet strength of paper, to creaseproof and stabilize dimensions of textiles such as cotton, viscose, wool, etc., and. to increase the durability of leather and bristles; and agents to seal off oil wells to prevent undesired seepage of liquids from confined places.

In connection with the foregoing uses, it is frequently desirable to employ the compositions obtained in the practice of this invention as coldsetting resins rather than as thermosetting resins; for example, when a urea-l-IMP composition is used as a plywood adhesive the curing of the adhesive can be accomplished by heating under pressure as hereinabove set forth, or pressure can be applied for a longer period (e. g. 24 hours) without the application of heat. A thickener such as walnut shell flour can be used in such applications, and this is desirable even when the HMP is thickened by the hereinabove described procedures, prior to adding the urea. Of course, when the composition is to be employed for the purpose of impregnating wood, no thickening step, and no added thickener, is desirable. The natural acidity of the Wood can be used to effect the cure at normal kiln temperatures.

While the invention has been described herein as applied to compositions obtained from phenol and formaldehyde, or phenol, formaldehyde and urea, it is to be understood that numerous other resin-forming ingredients may be substituted at least in part for the urea or for the phenol. Such resin-forming ingredients include thiourea, alkyl-substituted ureas, alkyl-substituted thioureas, melamine, alkyl-substituted melamines, dicyandiamide, guanidine, aniline, hexamethylenediamine, sulfonamides, adipamide, rescorcinol, cresol, t-butylphenol, phenylphenol, etc., and methylol derivatives thereof or mixtures of said resin ingredients or their methylol derivatives. The urea component may be introduced in the form of a higher methylolurea, such as those obtained by the process of the Kvalnes Reissue Patent 23,174. Moreover, such higher methylolureas can be modified by addition of phenol to produce HMP compositions, like those described herein, modified by urea.

Numerous embodiments of the invention will occur to those who are skilled in the art, and it is my intention that all such embodiments be ineluded within the scope of the pa e in en- ,t ion. I h

I claim:

process. forpreparinga stable; clear polymethylolphenol liquid which comprises heating from 4.0 to 10.0 v mols of monomeric formaldehyde per mol of phenol at a temperature within the rangeof C. to'lOO" C. at a pH Within the range of 7;0 'jto 9.5 until theffreeformaldehyde content ofthe resulting mixture is less than, 35% by weight, andc'ooling the mixture to below, .30

0,, saidfo'rm'aldehyde reactant being employed in the form of; aqueous formaldehyde containing 58% .to bywei'ght of' formaldehyde based j'onlthe totalweight offormaldhyde; plus water,

. said pl ienol reactantbeingemployed in the form of phenol containing not more than 20% by weight of water based on the weight of phenol plus water.

2. A process for preparing a stable, clear polymethylolphenol liquid which comprises heating from 4.0 to 10.0 mols of monomeric formaldehyde per mol of phenol at a temperature within the range of 60 C. to 100 C. at a pH within the range of 7.0 to 9.5 until the free formaldehyde content of the resulting mixture is less than 35% by weight, cooling the mixture to below 30 C. and adjusting the pH to from 4.5 to 6.8, said formaldehyde reactant being employed in the form of aqueous formaldehyde containing 58% to 65% by weight of formaldehyde based on the total weight of formaldehyde plus water, said phenol reactant being employed in the form of phenol containing not more than 20% by weight of water based on the weight of phenol plus water.

3. A process for preparing a stable, clear polymethylolphenol liquid which comprises heating from 4.0 to 10.0 mols of monomeric formaldehyde per mol of phenol at a temperature within the range of C. to C. at a pH within the range of 7.5 to 8.5 until the free formaldehyde content of the resulting mixture is less than 35% by weight, cooling the mixture to below 30 C. and adjusting the pH to from 5.5 to 6.5, said formaldehyde reactant being employed in the form of aqueous formaldehyde containing 58% to 65% by weight of formaldehyde based on the total weight of formaldehyde plus water, said phenol reactant being employed in the form of phenol containing not more than 20% by weight of water based on the weight of phenol plus water.

4. A polymethylolphenol composition obtained in accordance with the process of claim 1.

5. A polymethylolphenol composition obtained in accordance with the process of claim 2.

6. A process for preparing a viscous liquid resin-forming composition which comprises adjusting the pH of the composition of claim 4 to 7.5-9.5 and heating the resulting composition at a temperature of 70-l00 C. until the viscosity of the said composition has substantially increased.

7. A viscous liquid composition obtained in accordance with the process of claim 6. d

8. A process for preparing a viscous liquid resin-forming composition which comprises admixing urea with the composition of claim 6.

9. The composition obtained by the process of claim 8.

10. The method forv preparing a thermoset resin which comprises heating the composition of claim 9 in the presence of an acid catalyst mixing phenol with the compositionof claim 5,

ture Within the range of 70? to 100 C. until the viscosity thereofhas substantially increased.

12. The viscous liquid resin-forming composition obtained by the process of claim 11.

13. The method for preparing a thermoset resin which comprises heating the composition of claim 12 in the presence ofan acidic catalyst 12 at a temperature within the range of 120 to 175 C.

ole. A process for preparing a viscous liquid resin-forming composition which comprises "admixing phenol with the composition of claim4 and heating the resulting mixture at a tempera- .turt.within the range of 70 to 100 (lat a pH of 7.0 to 9.5 until the free formaldehydecontent reaches aivalue of less than 5% and the viscosity has substantially increased. A

15, A monomeric polymethylolphenol composition obtained by the process of claim 1' and containing 1.34 .to 3.0 methylol groups per unit of phenol. 5 j v HAMLINE M. KVALNES.

vNo references cited. 

1. A PROCESS FOR PREPARING A STABLE, CLEAR POLYMETHYLOLPHENOL LIQUID WHICH COMPRISES HEATING FROM 4.0 TO 10.0 MOLS OF MONOMERIC FORMALDEHYDE PER MOL OF PHENOL AT A TEMPERATURE WITHIN THE RANGE OF 60* C. TO 100* C. AT A PH WITHIN THE RANGE OF 7.0 TO 9.5 UNTIL THE FREE FORMALDEHYDE CONTENT OF THE RESULTING MIXTURE IS LESS THAN 35% BY WEIGHT, AND COOLING THE MIXTURE TO BELOW 30* C., SAID FORMALDEHYDE REACTANT BEING EMPLOYED IN THE FORM OF AQUEOUS FORMALDEHYDE CONTAINING 58% TO 65% BY WEIGHT OF FORMALDEHYDE BASED ON THE TOTAL WEIGHT OF FORMALDEHYDE PLUS WATER, SAID PHENOL REACTANT BEING EMPLOYED IN THE FORM OF PHENOL CONTAINING NOT MORE THAN 20% BY WEIGHT OF WATER BASED ON THE WEIGHT OF PHENOL PLUS WATER. 